There is an increased demand for materials which can be utilized to modify the flavor and/or fragrance of consumable items. The natural oils which have traditionally been used for this purpose often suffer the disadvantages of limited supply, high cost, and variable quality.
Accordingly, the search for synthetics which can function as partial or total replacements for essential oils, or which can find use in the creation of new and unique flavor and fragrance materials has intensified in recent years.
One specific example of a compound which can be prepared by the process of this invention is 2-isopropylidene-6,10-dimethylspiro[4.5]dec-6-en-8-one represented by the structure: ##STR3## one epimer of which is commonly referred to as .beta.-vetivone. It is a naturally occurring component of the oil obtained by steam distillation of the roots of Vetiveria zizanioides, and generally considered to be an important contributor to the overall odor character of the oil (Arctander, "Perfume and Flavor Chemicals," #3089, 1969).
Previous methods for the preparation of .beta.-vetivone have been set forth by Marshall and Johnson, J. Org. Chem., 1970, 35, 192; Yamada, Nagase, Hayakawa, Aoki and Hirata, Tetrahedron Lett., 1973, 4963; Stork, Danheiser and Ganem, J. Amer. Chem. Soc., 1973, 95, 3414; McCurry, Singh and Link, Tetrahedron Lett., 1973, 1155; Caine and Chu, Tetrahedron Lett., 1974, 703; Bozzar, Bachmann and Pesaro, J.C.S. Chem. Commun., 1974, 1005; Dauben and Hart, J. Amer. Cham. Soc., 1975, 97, 1622; Deighton, Hughes and Ramage, J.C.S. Chem. Commun., 1975, 662, Buchi, Berthet, Decorzant, Gieder and Hauser, J. Org. Chem., 1976, 41, 3209 and McCurry and Singh, Tetrahedron Lett., 1973, 3325.
Related references include Coxon, Price and Chee, Tetrahedron Lett., 1974, 2921; Hikino, Aota, Kuwana, and Takemoto, Tetrahedron, 27, 4831 (1971); and German Pat. No. 2,353,147 (1974).